The projection of the cervical disc and uncinate process on the posterior aspect of the cervical spine

BACKGROUND Surgical techniques of foraminotomy for decompression of the cervical nerve have been well described in the literature. Excessive resection of the facet joint and laminae may decrease segmental stability and increase scar formation. How much bony resection is adequate to remove a soft or hard disc herniation is not known. No studies regarding this subject are available. METHODS Thirty-nine adult dry bone spines from C3 to C7 were used and four measurements on each vertebra were taken in this study. The first three measurements included the vertical distances between the superior borders of the lamina and the vertebral body measured at the midline of the laminae, the middle of the lamina, and the lamina-facet junction, respectively. The fourth was the horizontal distance between the medial most border of the superior facet and the tip of the uncinate process. RESULTS No significant differences between male and female specimens were found in any measurements in this study. The mean vertical distances from the superior border of the lamina inferior to the superior border of the vertebral body measured at the three points for all levels were approximately 1-3 mm, although the standard deviations for those were relatively high. The tip of the uncinate process was located from 2 mm at C3 to 1 mm at C6 medial to the medial most border of the superior facet, and then changed to be located 1 mm lateral to the medial most border of the superior facet. CONCLUSIONS This study suggests that a semicircular laminotomy placed on the inferior aspect of the lamina above may be adequate for a lateral soft disc herniation because the inferior border of the disc is higher than the superior border of the inferior lamina, whereas a traditional foraminotomy is needed for a hard disc pathology. (C) 1999 by Elsevier Science Inc.